Strebel S-CB+ Series, Installation Operating & Maintenance Manual

Page: 19 / 125

S-CB
+
Boiler Range Manual
19
6.8 Frost protection
The boiler has a built-in frost protection that is automatically activating the central heating pump when the boiler
return (water) temperature drops below the 5°C (programmable). When the boiler return temperature drops below
the 3°C (programmable), the burner is also ignited. The pump and/or burner will shut down as soon as the return
temperature has reached the 10°C (programmable). The mentioned temperatures are related to the temperatures
measured by the RETURN sensor of the boiler. This frost protection function will not fire up the boiler in case of a
“general blocking” of the burner demand.
NOTICE: This
“Frost Protection” function is only useable for the boiler and not for the whole central heating system.
Because it concerns a programmable setting, a boiler damaged by frost is not covered under warranty.
6.9 Installing a strainer and/or dirt separator
Always install a strainer (water filter)
and/or a dirt separator in the return pipe
of the boiler; in such a way that the wa-
ter going to the boiler is free of any de-
bris/particles. When using a water filter
always check a week after installation to
determine the strainer cleaning interval.
Advice is to mount valves before and
after the strainer, including an air bleed
valve, so the strainer can be isolated
from the heating circuit for service op-
erations. Clean water is very important,
blocked and/or polluted heat exchang-
ers, including failures and/or damages
caused by this blockage are not covered
by the warranty.
6.10 Water quality
The pH value of the water must be within the following limits: 7,5 < pH < 9,5. This pH value is reached with the
steady conditions. These steady conditions will occur, when after filling the heating system (pH around 7) with fresh
water, the water will lose its air because of the air bleeding operation and heating up (dead water conditions).
Water hardness must be within the following limits:
3,5° Clark (50 ppm CaCO
3
) < total hardness < 10,5° Clark (150 ppm CaCO
3
)
When the water might contain aluminium particles, this should be of a maximum of 0.2 mg/litre. If there is the risk of
contamination of the water by any kind of debris/chemicals in the period after installing, a plate heat exchanger
should be used to separate the boiler circuit from the heating circuit (see drawing below).
It is advised to prevent the possible air intake and water leakage of the central heating system. Fresh oxygenated
water might damage the heat exchanger of the boiler and should therefore be prevented! Usual spots where air is
most likely to seep in are: suction gaskets, pumps, air valve working as a venting pipe, O-rings / gaskets in stuffing
box, under floor heating pipes.
SYSTEM WITH DIRT SEPARATOR
SYSTEM WITH STRAINER
SYSTEM WITH STRAINER AND DIRT SEPARATOR
DIRT SEPARATOR
DIRT SE-
PARATOR
WATER RE-
TURN FROM
SYSTEM
WATER
RETURN
FROM
SYSTEM
WATER
RETURN
FROM
SYSTEM
WATER FLOW
TO BOILER(S)
WATER FLOW
TO BOILER(S)
WATER
FLOW TO
BOILER(S)
DIRT
BLEED
VALVE
DIRT
BLEED
VALVE
AIR
BLEED
VALVE
AIR
BLEED
VALVE
VALVE
VALVE
VALVE VALVE
STRAINER
(WATER FILTER)
STRAINER
(WATER FILTER)